In a steam reformer, under high temperatures (e.g., 400-800° C.) and in the presence of a catalyst (e.g., nickel), steam may react with a feed gas (e.g., methane) to generate a reformate (e.g., hydrogen) which may be used as fuel in a hydrogen fuel cell to generate electricity, for example. In some examples, the steam is generated in a steam boiler which is coupled to the reformer. As a size of the steam reformer is reduced due to packaging constraints, for example, a size of the steam boiler should also be reduced.